A substantial number of freight trains, mainly with cement and aggregate, have to go from the London-bound goods lines into Acton Yard. This takes them across the line which will be used by eight crossrail trains per hour. To avoid disrupting Crossrail, its London-bound line is being put into a single-track tunnel under the freight lines. Westbound Crossrail will use one of the relief lines, eastbound will go through the diveunder.